1. Field of the Invention
The present invention is directed, in part, to methods and systems for enabling a service upgrade from one communication service standard to another communication service standard.
2. Description of the Related Art
Communication networks are evolving from circuit switched (CS) infrastructures towards packet switched (PS) infrastructures. A single common consolidated core network offers service providers the possibility of reducing core network complexity and maintenance. As service providers shift their core network infrastructure from the CS domain to a consolidated common internet protocol multimedia system (IMS) infrastructure, there is a need to enable the consistent provision of services to subscribers over a variety of accesses, including CS domain and PS domain accesses.
Initially, it can be expected that the coverage of internet protocol connectivity access networks (IP-CAN) capable of transporting bi-directional speech media will be limited compared to CS domain access networks at least during the introduction period of IP-CANs capable of transporting bi-directional speech media. The Third Generation Partnership Project (3GPP) standardization body is defining architecture to enable the use of a CS bearer for speech media while the service execution is moved to the IMS system. Therefore, a need exists to specify an architecture that supports the provision of IMS based services across a variety of PS domain or CS domain access networks. This would enable a consistent user-experience with bi-directional speech services of IMS subscribers irrespective of being inside or outside the coverage of an IP-CAN capable of transporting bi-directional speech media.
Additionally, global system for mobile communications (GSM) supplementary services have been well defined in the past. IMS supplementary services were specified in 3GPP Release 7 as part of multimedia telephony service (MMTel, 3GPP TS 24.173). GSM and IMS service sets are generally incompatible. For example, MMTel services in IMS domains contain far more granular service conditions when certain supplementary services are executed. Such services are generally impossible to provide in a GSM domain.
This deficiency leads to problems where a single user is using both CS and IMS domains, as it is not easy or possible to convert the data model from one domain to the other. For example, in an IMS domain, a user can set call forwarding services to a session initiation protocol (SIP) uniform resource identifier (URI) type of address (mysecretery@example.com) and if the user attempts to query call forwarding setting via CS it is impossible to present this information, since the GSM data model is only able to present E.164 numbers as a call forwarding destination.
Also, operators need to be able to deploy an IMS system that serves both subscribers using MMTel capable IMS user equipment (UE) and subscribers that use legacy (non-MMTel capable) GSM UEs that are connected to the IMS domain via network adaptor or gateway (L-CAAF-n or ICCF). The problem is how to ensure that one common IMS system is able to service subscribers in both service models (GSM and MMTel) and still ensure service consistency for each individual subscriber, i.e. ensure that the MMtel and GSM services are not mixed for a particular subscriber.